A voltage regulator accepts an unregulated and noisy supply voltage as an input and generates an accurate and well-defined output voltage with a rated current capacity. Generally, conventional voltage regulators consist of two functional parts, namely a bandgap voltage reference generation circuit and a voltage regulation circuit. FIG. 1 shows a conventional voltage regulator. In the FIG. 1 voltage regulator, each of the two parts has a separate feedback loop, where the noise and inaccuracy of each part cumulatively degrades the final, regulated output voltage.
U.S. Pat. No. 5,686,821 to Brokaw discloses a voltage regulator that has a single feedback loop. A defined bandgap voltage is not required in this voltage regulator. Instead, a separate proportional to absolute temperature voltage sensing stage is included along with a high-gain transconductance amplifier having an input offset voltage that cancels the proportional to absolute temperature voltage generated in the proportional to absolute temperature voltage sensing stage. The voltage regulator of U.S. Pat. No. 5,686,821 relies heavily on the accurate cancellation in one stage of the proportional to absolute temperature voltage generated in a different stage. In addition, the design of the voltage regulator of U.S. Pat. No. 5,686,821 requires a very high-gain transconductance amplifier to achieve the strong feedback loop required for accurate voltage regulation.